The 'last battle between Rut and Um,' 'Liwisblodrutum' is an apocalyptic battle in Xolhengian legend which, according to the legend, will occur when the demon Rut and the incarnation of the god Um both gather forces and engage one another in a war in the clouds. The result of the battle is believed to be the defeat of Rut, the clearing of Impendia's hydrocarbon smog, and the revelation of the 'City of Um.'